conditional format an empty cell

Anyone have a suggestion how I might be able to conditionally format an empty cell? I have a column formatted for numbers, which could contain anything from a "0" up numerically. The problem is that I might also have a cell which may not have anything in it and its those cells that I'd like conditionally format to a color. I thought I could use an IF formula like =IF(C2:C24<0,""), but that didn't work... Any help would be greatly appreciated. Thanks in advance! I see someone asked a similiar question and I found the answer... thanks...

Select cells C2:C24, click Format > Conditional Formatting

Change 'Cell value is' to 'Formula is', and use this formula:

=C2=""

Change the background color as needed and click OK. Those cells that are empty will now be the color you chose.